Watt-hour meters, most commonly used as electric energy billing meters, are simple induction electro-mechanical meters. These meters have proven to have a high degree of accuracy and reliability through many years of service under varying-ambient operating conditions. The reliability of these meters is exemplified by the fact that accrediting authorities in countries such as Canada require only sample testing of meters after which the meters can be sealed for a period of twelve years. This seal can be indefinitely extended for periods of up to eight years, depending upon the accuracy criteria of the testing. A conventional electro-mechanical induction meter typically lasts about thirty to forty-five years. The basic parts of the meter are assembled on a frame mounted on a base. A glass cover attaches to the base to form an enclosure for the meter components. The cover is sealed to the base and they are designed so that it is almost impossible to tamper with or make adjustments to the meter without leaving evidence.
The existing meter bases are made from a phenolic material, i.e. bakelite, and the current terminals slide through slots in the base. The terminals are held in place by a rubber gasket and metal washer on the inside and a cotter pin through the blade terminal on the outside. Assembly of this structure is labor intensive and requires a number of parts.
The current terminals project through the base mating with the terminal receptacle or meter box normally mounted on the side of a house or building and provides the electrical connection from the utility distribution network through the meter to the house or building. The current is carried through a current coil in a conventional manner and a potential coil inducing flux in the electro-magnetic system to rotate the rotor in response to and proportional to the energy being consumed.
In the known prior art meters a seal is formed between the glass and the base by an O-ring fitting into a channel in the base adjacent its outer perimeter. This gasket presses against the glass cover forming a seal. As it is necessary to have the gasket loose on the base to form a proper seal it is sometimes awkward and difficult to handle the meter when the glass cover is removed without having the gasket fall out of its channel.